One vertex per element, one color per generator, with an edge from x to x·s.
(2,6)(7,8)(10,12)(15,19)(16,20)(23,24)(25,26)(27,34)(28,32)(29,31)(30,33)(35,39)(36,40)(37,38) involution — undirected(1,2,5,6)(3,7,4,8)(9,10,14,12)(11,15,18,19)(13,16,22,20)(17,23,21,24)(25,27)(26,28)(29,34)(30,35)(31,32)(33,36)(37,39)(38,40)(10,12)(15,19)(16,20)(23,24)(26,29)(27,32)(30,38)(36,39) involution — undirected(1,3,5,4)(2,7,6,8)(9,11,14,18)(10,15,12,19)(13,21,22,17)(16,24,20,23)(25,28,31,34)(26,32,29,27)(30,39,38,36)(33,35,37,40)(1,3,5,4)(2,7,6,8)(9,12,14,10)(11,15,18,19)(13,20,22,16)(17,23,21,24)(25,29,31,26)(27,34,32,28)(30,37,38,33)(35,39,40,36)(1,4,5,3)(2,8,6,7)(9,13,14,22)(10,16,12,20)(11,17,18,21)(15,23,19,24)(25,30)(26,33)(27,35)(28,36)(29,37)(31,38)(32,40)(34,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.